2D/2D Heterostructured CdS/WS2 with Efficient Charge Separation Improving H2 Evolution under Visible Light Irradiation

Efficient water splitting for H2 evolution under visible light irradiation has attracted more attention for solving the global environmental and energy issues, but it is still a major challenge to develop an earth-abundant and efficient photocatalyst. Herein, we report two-dimensional (2D)/2D heterostructured CdS/WS2 (CdS/WS2), composed of nanosheet CdS (CdS) and nanosheet WS2 (WS2), as an efficient photocatalyst for H2 evolution. As a noble metal-free visible light-driven catalyst for H2 evolution, CdS/WS2 with 10 wt % WS2 exhibited the largest H2 evolution rate of 14.1 mmol g–1 h–1 under visible light irradiation to be 8 times larger than that of pure CdS. The lifetime and dynamics of photogenerated electrons were evaluated by femtosecond time-resolved diffuse reflectance spectroscopy, indicating that WS2 works as an electron-trapping site and a cocatalyst to cause H2 evolution under visible light irradiation. This work suggests that CdS/WS2 has great potential as a low-cost and highly efficient photocatalyst for water splitting.